On Sat, Jul 19, 2003 at 11:31:54AM -0500, Ronn!Blankenship wrote:
> Actually, it is because the soil is a _poor_ conductor of heat, so > it doesn't warm up rapidly in the summer or cool off rapidly in the > winter, so
Actually, no, it is not conductivity that primarily determines how rapidly something warms up with heat flow, it is heat capacity and mass. Of course, as I said, conductivity also comes into the formula but that primarily affects the distribution/homogeneity of temperature within the object.
In the case we are discussing, it is the insulating properties of the surface layers (soil on Earth, regolith on the Moon, etc.) which is what keeps the subsurface temperature constant year-round, which is what I thought the question was asking. That temperature is determined by the factors I mentioned: the luminosity and distance of the Sun, the albedo of the Earth, and the insulating effect of the atmosphere due to the greenhouse effect (plus any internal heat sources of the Earth): the Earth has had a long time to reach radiative equilibrium.
> _Vacuum_ is an awfully good insulator, and there's a lot of it outside > the habitat. ;-)
This is obvious but irrelevant to the question I was discussing.
> The surface temperature of the habitat would be almost entirely > determined by radiative equilibrium, taking into account the Sun's > luminosity and distance, the albedo of the exterior of the habitat, > and the amount of heat in excess of that coming from the Sun generated > by the people and equipment inside the habitat.
Yes, obviously. I didn't say anything different. But you aren't addressing the question, which was about the AIR inside the habitat. This will be greatly affected by the temperatures of the inside surfaces of the habitat in contact with the air. And as I said, the endcaps are not likely to be at the same temperature as the air in contact with the surfaces.
Are you suggesting that the air inside the habitat would be moving fast enough that it would not have time to heat up or cool down to the same temperature as the interior wall?
--Ronn! :)
I always knew that I would see the first man on the Moon.
I never dreamed that I would see the last.
--Dr. Jerry Pournelle
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